Spot the typo?

I spotted this while I was waiting for my bus and I took a double-take! Isn’t that a typo?

In my mind, I was just thinking of the implications, MacDonald’s will sack their agency, their agency will have to rectify the error and reprint all the ads and pay for the installation…. But wait a minute, after checking their website… apparently, it is NOT a spelling error but that’s how they spell “Filet-O-Fish” …! Now you know!